The present disclosure is generally related to wellbore operations and, more particularly, to positive indication of the proper actuation of a downhole tool.
Hydrocarbon-producing wells are often stimulated by hydraulic fracturing operations in order to enhance the production of hydrocarbons present in subterranean formations. During a typical fracturing operation, a servicing fluid (i.e., a fracturing fluid or a perforating fluid) may be injected into a subterranean formation penetrated by a wellbore at a hydraulic pressure sufficient to create or enhance fractures within the subterranean formation. The resulting fractures serve to increase the conductivity potential for extracting hydrocarbons from the subterranean formation.
In some wellbores, it may be desirable to strategically generate multiple fractures along the wellbore at predetermined distances apart from each other, thereby creating multiple “pay zones” in the subterranean formation. Some pay zones may extend a substantial distance along the axial length of the wellbore. In order to adequately fracture the subterranean formation encompassing such pay zones, it may be advantageous to introduce a stimulation fluid via multiple stimulation assemblies arranged within the wellbore at spaced apart locations on a work string extended therein. Each stimulation assembly, commonly referred to as sliding sleeve assemblies, may include, for example, a sliding sleeve configured to be opened and/or shut in order to regulate fluid communication between the interior of the work string and the surrounding subterranean formation.
In some applications, the sleeve may be opened or otherwise actuated by introducing a wellbore projectile, such as a ball or a dart, into the work string. The wellbore projectile is conveyed to the location of the sleeve and engages an internal baffle or seat defined on the interior surface of the work string. Once the wellbore projectile is properly seated on its corresponding internal baffle, the work string is pressurized to a predetermined pressure and the increased pressure serves to actuate the sleeve via a variety of mechanical or hydraulic means. As measured at the surface, the predetermined increased pressure also serves as an indicator that the sleeve has opened or otherwise has been moved as planned.
In some cases, however, the increased pressure in the work string does not actually result in the movement of the sleeve. Instead, the increased pressure can sometimes force the wellbore projectile to extrude past the baffle without actually causing the sleeve to actuate. Nevertheless, in such cases, the increased pressure is measured at the surface and erroneously informs an operator that the sleeve has moved when in reality the sleeve has remained stationary throughout the pressurization process. As a result, subsequent wellbore operations requiring the sleeve to have moved as planned will be ineffective and result in lost time and costs.